Activated carbon‐based magnetic composite as an adsorbent for removal of polycyclic aromatic hydrocarbons from aqueous phase: Characterization, adsorption kinetics and isotherm studies

Abstract

This study investigated the preparation, characterization, and capacity of a magnetic powder activated carbon (MPAC) composite to remove polycyclic aromatic hydrocarbons (PAHs) from aqueous solutions. The iron oxide nanoparticles deposited on the PAC surface enabled the adsorbent to be simply and rapidly recovered from the solutions using a magnetic field. The PAH compounds were adsorbed on the MPAC surface through π-π and H-π interactions based on the peak position changes observed in the FTIR spectra of MPAC after adsorption. The PAHs adsorption by MPAC was relatively fast, reaching equilibrium in 6 h with the removal efficiency ranging from 95.6 to 100.0%. The pseudo-second order model exhibited the best fit of the kinetics data, suggesting that all the MPAC adsorption sites had an equal affinity for the PAHs compounds and the adsorption process was chemical. The results of the kinetics experiments also indicated the slower adsorption rate of the higher molecular weight PAHs due to the slower transfer of these analytes to the accessible adsorption sites of MPAC. The Langmuir model best described the isotherm adsorption of both low molecular weight (LMW) and high molecular weight (HMW) PAHs, with an R2 in the range of 0.73–0.96. This model also showed that the MPAC particles had a maximum adsorption uptake ranging from 8.74 to 11.37 µg/mg for the LMW PAHs and 8.43 to 20.21 µg/mg for the HMW PAHs, respectively.